Receiver



Feb. 15, 1938.

J. M, UNK

RECEIVER Original Filed Aug. 3, 1929 llllllll vIv vvv INVENTOR JACB M- um BY Patented Feb. 15, 1938 LLUNITED STATES PATENT OFFICE 2,108,458 RECEIVER Application August 3,

1929, Serial No. 383,243.

Renewed April 6, 1936. In Germany August 28, 1928 8 Claims.

The invention has reference to a wireless receiving set which is entirely energized by alterhating current and which has housed in it a device for this purpose. In addition, the wire- 5 less receiving set is so constructed as to permit of the local broadcasting emitter being rendered audible in the loudspeaker. In constructing the set the smallest possible external dimensions of the aggregate have been endeavored to be obtained. i

The receiving set comprises a detector and a low frequency amplifying stage and has housed in ita public supply transformer the secondary coil or coils of which supply'the alternating current for the power supply to the cathodes of a detector and an outputvalve respectively, and energizes asingle rectifier valve with smoothing device for the plate voltage and grid bias of the said detector and output valve. The expression public supply transformer is to be understood to mean a transformer the primary of which is connected for the operation of the set to the public alternating current supply or other local source of alternating current.

In addition-the 'set comprises connecting devices for an electric pick-up which enables the latter to be inserted in the grid circuit of the detector valve.

In accordance with the. present invention means are provided whereby the grid biasing potential of the thermionic tube normally acting as a detector is changed automatically when the pick-up is inserted to a value at which the "tubes operate as an amplifier.

The setis exceptionally handy to use. For

its operation it simply suflices to establish the' connection to the public alternating current supply, gramaphone musicequally well as the local broadcasting emitter being thus enabled to be rendered audible in the loudspeaker. The. set need only comprise three Valves and its external dimensions are 19 x 19 x 27 centimeters which constitutes an exceptionally small construction shown, the incandescent cathode of valve D is heated indirectly. The coil S4 supplies the filament current for the rectifier valve R which rectifies the current passing through coil S2. The rectified current is smoothed by impedances and condensers approximately as shown in the diagram. The plate voltage for the valve D, the plate voltage for the valve L and the negative grid bias for the valve L are branched respectively off the resistances in; II and coil l2. In addition the set comprises two connecting devices l3 and M for an electric pick-up inserted in' the grid circuit of the valve D. On connection of this pick-up the oscillations thereby generated are strengthened by two amplifying stages and will be audible as such in the loudspeaker.

When the thermionic tube is acting as a detector of radio signals, bias for the grid of the tube is supplied from the filter network I2, [0,

H, via resistances l6 and i5. When the electri"" cal pick-up is inserted in the input circuit of the thermionic tube D the biasing potential is supplied from the filter net work via parallel paths H, the pick-up to the grid of D and I6, I5 to the grid of D. e t

It will also be noted that an impedance preceded by a grounded condenser is inserted in the connection between each electrode of each valve and the power source network.

I claim:

1. In a radio receivenan electronic tube provided with an anode, a cathode and a grid electrode, a source of anode current, a connection from the anode of the tube to'the cathode thereof including said source and a resistor element in series, a connection from the grid of the tube to the cathode thereof, said connection including a portion of said resistor whereby the included portion of the resistor is both in the grid and plate circuits of thetube, a pair of terminals for connection of an electrical pick-up device, a direct connection from one of said terminals to the grid of the tube and a direct connection from the other of said terminals to the cathode of said tube said last named connection also including at least a portion of said resistor.

2. In a relay circuit, an electronic tube provided with an anode, a cathode and at least one grid electrode, a source of uni-directional space current for said tube, said source being provided with a positive terminal and a negative terminal, a connection including an impedance device between the anode of said tube and the positive terminal of the source, a connection between the negative terminal of the source and the cathode of the tube, said last named connection comprising a chain of resistance and inductance elements in series, means for biasing a grid electrode of said tube with respect to the cathode thereof comprising a connection between the cathode and the grid electrode, said connection including at least a portion of said chain of resistance and inductance elements, a second electronic tube having anode, cathode and grid electrodes, means connecting the anode and cathode electrodes of said second tube to the positive and negative terminals respectively of the source, and means including at least a portion of said chain of resistance and inductance elements for connecting the grid electrode of the second tube to the cathode thereof.

3. In an amplifier circuit, an electronic tube provided with an anode, a cathode and at least one grid electrode, a source of uni-directional fluctuating current, said source being provided with positive and negative terminals, a filter condenser efiectively across the source, means connecting the space path of said electronic tube across said source comprising a connection between the anode of the tube and said positive terminal and a connection between the cathode of the tube and said negative terminal, said last named connection including an inductance element and a resistance element in series, means for biasing the grid of the tube with respect to the cathode thereof comprising a connection between the grid of the tube and the cathode thereof, said connection including a filter impedance and one of said elements in series and a filter condenser shunting both the filter impedance and the last named element.

4. In a signalling circuit, a pair of electronic tubes each thereof being provided with anode, cathode and grid electrodes, a source of fluctuating uni-directional current said source being provided with positive and negative terminals, filtering means effectively in shunt with said source, means for connecting the space path of one of said tubes across said source to thereby establish a flow of space current therethrough comprising a connection between the anode of said last named tube and the positive terminal of said source and a connection between the cathode of the tube and the negative terminal of the source, said last named connection including a filter inductance element and an impedance element, means for biasing the grid of the last named tube with respect to the cathode thereof comprising a connection between the grid and the cathode including a filter impedance device and one of said elements in series and a filter condenser shunted across the filter impedance and said element, means for connecting the other of said tubes across said source comprising means connecting the anode of the last named tube to the positive terminal of the source and means, including said filter inductance element and impedance element, connecting the cathode of the last named tube to the negative terminal of the source, means for biasing a grid of the last named tube with respect to the cathode thereof comprising a connection between the grid and cathode thereof said connection including a filter resistor device, said filter inductance element and said impedance element in series and a filter condenser device shunted between said grid electrode and the cathode.

5. In a signalling circuit, a pair of cascaded electronic tubes, said tubes being provided with anode, cathode and grid electrodes, a source of space current having negative and positive terminals, means for maintaining the anodes of said tubes at a positive potential with respect to the cathodes thereof comprising means connecting the anodes of said tubes to the positive terminal of the source and means including a resistance element and an inductance coil forming a series circuit for connecting the cathodes of the tube to the negative terminal of the source, means for biasing the grid of one of said tubes with respect to the cathode thereof comprising a connection between the last named grid and a point of the last named series circuit and means for differently biasing the grid of the other of said tubes with respect to the cathode thereof comprising a connection between the last named grid and a different point of said series circuit.

6. In a relay circuit, an electronic tube provided with an anode, a cathode and a grid electrode, a source of space current, said source having positive and negative terminals, a circuit connected between the positive and negative terminals of said source and comprising a chain of impedance elements and a condenser in series, means connecting the anode of the electronic tube to the positive terminal of the source, means including the chain of impedance elements for connecting the cathode of the tube to the negative terminal of the source, means for biasing the grid electrode of the electronic tube, said last named means comprising a connection between the grid electrode of the tube and the negative terminal of the source and including only a portion of the chain of impedances, a second electronic tube having an anode, a cathode, a grid electrode and an auxiliary electrode, means for connecting the anode to the positive terminal of the source, means for connecting the auxiliary electrode to the positive terminal of the source, means for connecting the cathode of the second electronic tube to the cathode of the first tube and means for potentializing the grid electrode of the second tube with respect to the cathode thereof comprising a connection between the grid electrode and a point of said chain of impedances.

'7. In a relay circuit, a pair of electronic tubes having anode, cathode and grid electrodes, a source of space current for said tubes, said source being provided with a negative terminal and a positive terminal, means including a resistor and an inductance coil in series for connecting the cathodes of the tubes to the negative terminal of the source, means connecting the anodes of the tubes to the positive terminal of the source, means for biasing the grid electrode of one of said tubes comprising a grid-cathode circuit for said tube, said grid-cathode circuit including a filter resistor and the first-named resistor in series and a filter condenser connected across said series filter resistor and first named resistor, and, means for biasing the grid electrode of the other of said tubes comprising a grid-cathode circuit for said other tube, said last named gridcathode circuit including a filter resistor and at least a part of said inductance coil in series, and a filter condenser connected across said last named series resistor and coil.

8. In a relay circuit, a first electronic tube provided with anode, cathode and grid electrodes, and a second electronic tube provided with anode, cathode and grid electrodes, a source of space current for said tubes, said source being provided with a negative terminal and a positive terminal, means including a resistor and an inductance coil in series for connecting the cathodes of the tubes to the negative terminal of the source, means connecting the anodes of the tubes to the positive terminal of the source, means for biasing the grid electrode of the first of said tubes comprising a connection between the grid 1 electrode of the first of said tubes and the oathode thereof, and including a filter resistor and the first named resistor in series, a by-pass con- 

